The present invention relates to a surfactant composition, and a degreasing composition and a degreasing bath containing the surfactant composition, and more particularly to a surfactant composition suitable for a degreasing composition having excellent detergency and antifoaming properties at room temperature, and a degreasing composition and a degreasing bath containing such a surfactant composition.
In the chemical coating of metal surfaces, degreasing is usually conducted to remove oil substances (mineral oils, animal or vegetable fats and oils, etc.) from the surfaces of metal members to be formed with chemical coatings.
Degreasing detergents used fox degreasing treatments contain as main components builders based on acids or alkalis and nonionic surfactants, and they are used in the form of aqueous solutions by a spraying method or an immersion method at 40.degree.-70.degree. C. for 1-10 minutes.
However, in view of the recent demands of saving energy, detergents capable of removing oils at lower temperatures such as 5.degree.-40.degree. C. are desired.
As such detergents, Japanese Patent Laid-Open No. 61-60892 discloses an alkali detergent usable at room temperature which contains polyoxyalkylene alkyl ether as a surfactant. The polyoxyalkylene alkyl ether in this detergent has the following general formula: EQU RO(EO).sub.m (PO).sub.n H,
wherein
R: Alkyl group, PA1 EO: Ethylene oxide group, PA1 PO: Propylene oxide group, and PA1 m,n: Mol. PA1 a compound (a) represented by the general formula (1): EQU R.sup.1 O(AO).sub.n H (1) PA1 wherein R.sup.1 is a substituted or unsubstituted hydrocarbon group having 6 or more carbon atoms; A is at least one group selected from the group consisting of an ethylene group, a propylene group, a butylene group and a styrene group, provided that an ethylene group in A is 5 mol or more per 1 mol of R.sup.1, and that the ethylene group is 50 mol % or more per 100 mol % of said A; and n is an integer of 5-50; PA1 a compound (b1) represented by the general formula (2): ##STR5## wherein R.sup.2 is a substituted or unsubstituted hydrocarbon group having 6 or more carbon atoms, E is an ethylene group and n is an integer of 1-20; and PA1 a compound (b2) represented by the general formula (3): ##STR6## wherein R.sup.2, E and n are the same as in the formula (2), a weight ratio of compound (a)/(compound (b1)+compound (b2)) being 10/90-95/5, and a weight ratio of compound (b2)/compound (b1) being 20/80 or more. PA1 a compound (a) represented by the general formula (1): EQU R.sup.1 O(AO).sub.n H (1) PA1 wherein R.sup.1 is a substituted or unsubstituted hydrocarbon group having 6 or more carbon atoms; A is at least one group selected from the group consisting of an ethylene group, a propylene group, a butylene group and a styrene group, provided that an ethylene group in A is 5 mol or more per 1 mol of R.sup.1, and that the ethylene group is 50 mol % or more per 100 mol % of said A; and n is an integer of 5-50; PA1 a compound (b1) represented by the general formula (2): ##STR7## wherein R.sup.2 is a substituted or unsubstituted hydrocarbon group having 6 or more carbon atoms, E is an ethylene group, and n is an integer of 1-20; and PA1 a compound (b2) represented by the, general formula (3): ##STR8## wherein R.sup.2, E and n are the same as in the formula (2), a weight ratio of compound (a)/(compound (b1)+compound (b2)) being 10/90-95/5, and a weight ratio of compound (b2)/compound (b1) being 20/80 or more, and further comprising an alkali builder in a weight ratio [(compound (a)+compound (b1)+compound (b2))/alkali builder] of 1:0.1-1:2,000. PA1 (I) 0.005-0.5 weight % of a surfactant composition comprising: PA1 (II) 0.05-10 weight % of an alkali builder.
However, although this detergent has improved detergency at room temperature, the level of detergency is still insufficient.
U.S. Pat. No. 3,010,907 to Carroll discloses a non-foaming alkaline cleaning composition comprising a major proportion of an inorganic alkaline material, from 0.05% to 5% by dry weight of the composition of an organic detergent, and from 0.01% to 1% by dry weight of the composition of a defoamer, the inorganic alkaline material being selected from the class consisting of caustic soda, caustic potash, sodium carbonate, sodium bicarbonate, alkali metal silicates, alkali metal phosphates, and mixtures thereof, the organic detergent being an alkyl phenol-ethylene oxide condensation product having the formula: ##STR3## wherein R is an alkyl group having 9 carbon atoms and where n has a value of from 8 to 10, and the defoamer being a phosphate ester of the formula: ##STR4## wherein the C.sub.8 H.sub.17 radical is a 2-ethyl hexyl group and where n has a value of approximately 4 to 6.
However, since a phosphate monoester is used as the phosphate ester in this cleaning composition, sufficiently high cleaning power cannot be achieved at a low foaming level.